JPWO2013141400A1 - Porous glass plate and detector for electron amplification - Google Patents

Abstract

Used in a detector (1) for measuring ionization electrons using electron avalanche amplification in gas, and provided with a plurality of through holes (14) two-dimensionally arranged in a plate-like member (11). In order to realize thinning of the glass plate and miniaturization of the through hole (14), the plate member (11) is obtained by crystallizing photosensitive glass. It is formed of photosensitive crystallized glass.

Description

  The present invention relates to an electron amplification pore glass plate and a detector configured using the electron amplification pore glass plate.

  In recent years, detectors that use electron avalanche amplification by a gas electron amplifier (hereinafter referred to as “GEM”) are known as detectors that detect particle beams or electromagnetic waves. In general GEM, a plate-like film member made of polyimide or the like having a thickness of about 50 μm is formed with a plurality of through-holes penetrating the front and back, and both sides of the film member are covered with copper. And an electronic amplification substrate. Then, with the electronic amplification substrate placed in the detection gas, a copper thin film covering both surfaces of the film member is used as an electrode to give a potential difference between the two electrodes, and a strong electric field is generated in the holes of the plurality of through holes. It is configured to enable measurement of ionized electrons in the detection gas by creating and amplifying the electron avalanche by the electric field and increasing the number of ionized electrons so that it can be captured as a signal (for example, Patent Document 1).

  However, since the GEM configured as described above uses a film member made of polyimide or the like, there are problems that heat resistance, smoothness, rigidity, etc. are low and outgas may occur. From this, for detectors that detect particle beams or electromagnetic waves, as a base material for an electronic amplification substrate, a substrate made of lead-free soda-lime glass (see, for example, Patent Document 2) or an inorganic material such as heat-resistant glass It has been proposed to use a substrate made of (for example, see Patent Document 3).

JP 2006-302844 A Japanese Patent No. 4058359 JP 2009-301904 A

As a base material for an electronic amplification substrate for use as a particle beam or electromagnetic wave detector, it is preferable to use a glass substrate instead of a film member made of polyimide or the like from the viewpoint of heat resistance as described above. However, with glass substrates such as soda-lime glass and heat-resistant glass, the thickness is limited to about 250 μm even if it is thin, and it is very possible to achieve a thickness equivalent to a film member made of polyimide or the like. Have difficulty. This is because if the thickness is less than about 250 μm, cracking due to insufficient strength may occur. If no cracking or the like occurs, it is preferable that the glass substrate (hereinafter referred to as “electron amplification pore glass plate”) serving as the base material of the electronic amplification substrate is made thinner. One of the reasons is as follows. In the electron avalanche amplification, electrons are amplified in the through hole. At this time, if the thickness of the electron amplification pore glass plate is large and the hole diameter of the through hole is small, there is a high possibility that electrons will adhere to the wall surface in the hole before passing through the through hole. As a result, there is a possibility that a sufficient electron amplification degree (gain) cannot be obtained. In other words, if the thin glass plate for electron amplification is made thin without causing cracks and the like, and the inner wall area of the through hole is suppressed, the potential difference applied between the electrodes is not increased more than necessary. However, since it becomes possible to obtain a sufficient gain in the amplification of the electronic avalanche, it is very suitable as a detector application using the electronic avalanche amplification.
In addition, it is preferable that the pore diameter and the arrangement pitch are made finer for a plurality of through-holes penetrating the front and back surfaces of the fine glass plate for electron amplification used as a particle beam or electromagnetic wave detector. This is because the hole diameter and arrangement pitch of the through-holes directly affect the detection resolution, and in order to improve the detection resolution, it is necessary to refine the hole diameter and arrangement pitch. However, for glass materials such as soda-lime glass and heat-resistant glass, it is conceivable to form through holes by machining such as a fine powder injection method, but in that case, formation with a hole diameter of about 100 μm and an array pitch of about 150 μm is the limit. It is very difficult to perform finer processing than that. Furthermore, it is difficult to reduce the thickness of glass materials such as soda-lime glass and heat-resistant glass as described above, and this is also an obstacle to realizing finer hole diameters and arrangement pitches.

  Accordingly, an object of the present invention is to provide an electron amplification pore glass plate and a detector that can realize thinning and finer through-holes even if the forming material is glass.

The present invention has been devised to achieve the above object.
In order to achieve this object, the inventors of the present application first examined the miniaturization of the hole diameter and arrangement pitch of the through holes. For miniaturization of the hole diameter and arrangement pitch of the through holes, it is effective to use, for example, a fine processing technique used in a semiconductor manufacturing process. Therefore, the inventors of the present application paid attention to photosensitive glass. The photosensitive glass is configured so that selective etching with hydrogen fluoride (HF) can be performed only on a photosensitive portion by exposure, and is a material that can be finely processed while taking advantage of the characteristics of the glass.
However, with photosensitive glass, it is difficult to realize thinning even if fine processing is possible. This is because even if it is a photosensitive glass, if it is attempted to reduce the thickness, cracks due to insufficient strength will occur as in the case of soda-lime glass or heat-resistant glass. In other words, the photosensitive glass is an amorphous solid like soda lime glass or heat-resistant glass, and it is not always necessary to make such an amorphous solid glass as thin as a film member made of polyimide or the like. It may not be easy to implement.
In this regard, the inventors of the present application have further studied earnestly. And if it is a photosensitive crystallized glass obtained by crystallizing a photosensitive glass instead of the photosensitive glass itself, a microfabrication technology used in the semiconductor manufacturing process even when using a glass that is a brittle material It came to the idea that sufficient strength that can realize thinning could be obtained while making it possible to use this material. The photosensitive crystallized glass here is a product obtained by heat-treating the photosensitive glass and depositing fine crystals uniformly in the glass, and is in a polycrystalline state in which crystallization has progressed completely. Excellent mechanical properties compared to amorphous ones.
This invention is made | formed based on the new knowledge by the present inventors mentioned above.

A first aspect of the present invention is a pore glass plate for electron amplification used in a detector for measuring ionized electrons using electron avalanche amplification in gas, and is two-dimensionally arranged on a plate-like member A plurality of through-holes, and the plate-like member is formed of photosensitive crystallized glass obtained by crystallizing photosensitive glass. is there.
According to a second aspect of the present invention, in the invention described in the first aspect, the photosensitive crystallized glass has a bending strength in a state where the through hole is not formed, which is greater than 150 MPa.
According to a third aspect of the present invention, in the invention according to the first or second aspect, the plurality of through holes are formed with a hole diameter of 100 μm or less.
According to a fourth aspect of the present invention, in the invention according to any one of the first to third aspects, the plurality of through holes are formed with an arrangement pitch of 400 μm or less.
According to a fifth aspect of the present invention, in the invention according to any one of the first to fourth aspects, the plate-like member is formed to have a plate thickness of 500 μm or less.
According to a sixth aspect of the present invention, the plate-like member is provided with a plurality of through holes arranged two-dimensionally, and the plate-like member is formed of photosensitive crystallized glass obtained by crystallizing photosensitive glass. And a conductive layer formed on the front and back surfaces of the electron amplification pore glass plate, and a potential difference is provided between the front and back surfaces so that the inside of the through hole An electron avalanche amplification caused by an electric field formed in the through-hole in the gas, and an electrode for forming an electric field in the gas, a chamber for arranging the electrode in the gas and the pore glass plate for electron amplification This is a detector configured to perform measurement on ionized electrons by using.

  According to the present invention, even when glass is used as the material for forming the electron amplification pore glass plate, the electron amplification pore glass plate is thinned and formed on the electron amplification pore glass plate. It is possible to reduce the diameter of the through holes and the arrangement pitch.

It is explanatory drawing which shows the schematic structural example of the detector in embodiment of this invention. It is explanatory drawing which shows the typical characteristic of the photosensitive crystallized glass and photosensitive glass in embodiment of this invention. It is explanatory drawing which shows an example of the manufacture procedure of the pore glass plate for electronic amplification in embodiment of this invention. FIG. 3 is an explanatory view showing a main part plan shape of an electronic amplification pore glass plate in Example 1; It is explanatory drawing which shows the electric field convergence state in Example 1. FIG. It is explanatory drawing which shows an example of the electronic avalanche amplification in Example 1. FIG. It is explanatory drawing which shows the other example of the electronic avalanche amplification in Example 1. FIG. FIG. 6 is an explanatory view showing a main part plan shape of an electronic amplification pore glass plate in Example 2; FIG. 6 is an explanatory diagram showing an electric field convergence state in Example 2. It is explanatory drawing which shows an example of the electronic avalanche amplification in Example 2. It is explanatory drawing which shows the other example of the electronic avalanche amplification in Example 2. 6 is an explanatory diagram showing a test setup state in Example 3. FIG. It is explanatory drawing which shows the gain characteristic in the case of the electronic avalanche amplification in Example 3. It is explanatory drawing which shows the energy resolution of the energy spectrum in Example 4. FIG. 10 is an explanatory diagram showing a drift test in Example 5. FIG. It is explanatory drawing which shows the irradiation channel dependence of the peak channel of an energy spectrum in Example 6, and energy resolution. It is explanatory drawing which shows the irradiation position dependence of the peak channel of the energy spectrum in Example 7. FIG. It is explanatory drawing which shows the gain characteristic in the case of the electronic avalanche amplification in Example 8.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
In the present embodiment, description will be made by dividing into items in the following order.
1. 1. Schematic configuration of detector 2. Structure of the electron amplification pore glass plate 3. Production procedure of pore glass plate for electron amplification 4. Procedure for measuring ionized electrons in the detector Effects of the present embodiment 6. Modifications etc.

<1. Schematic configuration of detector>
First, a schematic configuration of the detector in the present embodiment will be described.
The detector can measure ionized electrons by using electron avalanche amplification in a detection gas, and is configured to detect particle beams or electromagnetic waves.

  “Electron avalanche amplification” used by the detector means that when a free electron collides with a gas molecule in a strong electric field, a new electron is knocked out, and this is accelerated by the electric field and collides with another molecule to accelerate it. The phenomenon that the number of electrons increases. Detectors that use electronic avalanche amplification include, for example, a gas proportional counter (CGPC). In this embodiment, a detector that causes electronic avalanche amplification using GEM is called a detector.

  Here, “GEM” refers to a state where an electronic amplification substrate having a plurality of fine through holes arranged two-dimensionally is arranged in a detection gas, and a strong electric field is generated in the through hole of the electronic amplification substrate. The one created and configured to cause electronic avalanche amplification by the electric field. The electronic amplification substrate may be a single plate or a plurality of layers may be multilayered.

  “Particle beams” that can be detected by detectors include alpha rays, beta rays, proton beams, heavy charged particle beams, electron beams (those that accelerate electrons with an accelerator regardless of nuclear decay), neutron beams, and space. Lines etc. are included. The “electromagnetic wave” includes radio waves (low frequency, super long wave, long wave, medium wave, short wave, ultra short wave, microwave), light (infrared ray, visible ray, ultraviolet ray), X-ray, gamma ray and the like. Which of these is to be detected can be set as desired by appropriately selecting the type of detection gas, the strength of the electric field to be created, and the like.

The detector in the present embodiment as described above, that is, the detector that detects the particle beam or the electromagnetic wave by using the electron avalanche amplification by the GEM is specifically configured as described below.
FIG. 1 is an explanatory diagram illustrating a schematic configuration example of a detector according to the present embodiment.

  The illustrated detector 1 includes a drift electrode 3 and a readout electrode 4 in a chamber 2 filled with a predetermined type of detection gas, and is disposed between the drift electrode 3 and the readout electrode 4. An electronic amplification substrate 10 is provided. The electronic amplification substrate 10 realizes the function as a GEM by causing electronic avalanche amplification, and a plurality of through holes 14 are two-dimensionally formed in a laminate 13 in which conductive layers 12 are formed on both surfaces of a plate-like member 11. It is arranged and configured. The plurality of through-holes 14 each have a circular shape when the electronic amplification substrate 10 is viewed in plan, and are arranged at regular intervals. The chamber 2 is configured so that particle beams or electromagnetic waves to be detected can enter from the outside.

  A predetermined voltage is applied to the drift electrode 3 and the readout electrode 4 in the chamber 2 from a power supply unit (not shown). Furthermore, a predetermined voltage is applied from a power supply unit (not shown) to each conductive layer 12 on both surfaces of the electronic amplification substrate 10 by functioning as an electrode. By such voltage application from the power supply unit, an electric field E1 is generated in a region 5 (hereinafter referred to as “drift region”) between the drift electrode 3 and the electronic amplification substrate 10, and the electronic amplification substrate 10 and the readout electrode are generated. An electric field E3 is generated in a region 6 between 4 (hereinafter referred to as “induction region”) 6. An electric field E2 is generated in the through hole 14 of the electronic amplification substrate 10. And the electric field E2 is converged in the hole of the through-hole 14, and the electron which entered here is accelerated, and an electron avalanche amplification arises. The detector 1 is configured to measure the electron multiplied by the electron avalanche amplification with the readout electrode 4 and output the measurement result through an electric circuit for signal readout (not shown) connected to the readout electrode 4. Has been.

  In the detector 1 having the above-described configuration, the plate-like member 11 constituting the electronic amplification substrate 10 serves as a base material of the electronic amplification substrate 10. In this case, it is preferable that the thickness of the plate and the through hole 14 can be reduced. For this reason, the detector 1 according to the present embodiment includes the electronic amplification substrate 10 using an electronic amplification pore glass plate as described below.

<2. Structure of pore glass plate for electron amplification>
Next, the configuration of the electronic amplification pore glass plate in the present embodiment will be described.
The electron amplification pore glass plate is formed by providing a plurality of through holes 14 two-dimensionally arranged on a plate-like member 11 made of glass, that is, glass capillaries are regularly arranged in parallel. It is bundled and formed into a plate shape, and is particularly configured to be capable of causing an avalanche amplification effect in gas. When the conductive layer 12 functioning as an electrode is formed on the front and back surfaces of such an electronic amplification pore glass plate, the electronic amplification substrate 10 is configured.

  The pore glass plate for electronic amplification in the present embodiment is greatly characterized in that it is formed of photosensitive crystallized glass obtained by crystallizing photosensitive glass.

“Photosensitive glass” is a glass containing SiO ₂ —Li ₂ O—Al ₂ O ₃ glass, a small amount of Au, Ag, Cu as a photosensitive metal, and CeO ₂ as a sensitizer.
Photosensitive glass undergoes an oxidation-reduction reaction by irradiating with ultraviolet rays to generate metal atoms. When further heated, metal atoms aggregate to form a colloid, and a crystal of Li ₂ O.SiO ₂ (lithium metasilicate) grows with this colloid as a crystal nucleus. Li ₂ O.SiO ₂ (lithium metasilicate) deposited here is easily dissolved in HF, and there is a difference in dissolution rate of about 50 times compared to the glass part not irradiated with ultraviolet rays. By utilizing this difference in dissolution rate, selective etching can be performed, and a fine workpiece can be formed without using machining.
Examples of such photosensitive glass include “PEG3 (trade name)” manufactured by HOYA Corporation.

In addition, “photosensitive crystallized glass” means that the photosensitive glass is subjected to a heat treatment (a heat treatment under conditions different from those when fine processing is performed on the photosensitive glass), so that the glass is uniformly fine. Crystals are precipitated. The crystals deposited here are excellent in chemical durability, unlike crystals of Li ₂ O.SiO ₂ (lithium metasilicate). Therefore, since the photosensitive crystallized glass is in a polycrystalline state in which crystallization has completely progressed, the photosensitive crystallized glass has an advantage of excellent mechanical characteristics as compared with the photosensitive glass that is an amorphous solid.
Examples of such photosensitive crystallized glass include “PEG3C (trade name)” manufactured by HOYA Corporation.

Here, typical characteristics of “PEG3C”, which is a photosensitive crystallized glass, are shown in FIG. 2 together with typical characteristics of “PEG3”, which is the photosensitive glass on which the photosensitive glass is based.
As is clear from the example of the drawing, the photosensitive crystallized glass has excellent mechanical properties compared to the photosensitive glass. Specifically, the bending strength of “PEG3” is larger than 65 MPa, whereas the bending strength of “PEG3C” is larger than 150 MPa, and “PEG3C” has a higher bending strength. .
Therefore, for example, when formed with “PEG3C”, the bending strength in the state where the through hole 14 is not formed in the electronic amplification porous glass plate is larger than 150 MPa.

Furthermore, “PEG3C”, which is a photosensitive crystallized glass, has a volume resistivity of about 10 ¹⁴ Ωm. Therefore, it can be said that it is difficult to be charged due to the low insulation resistance as compared with polyimide having a volume resistivity of 10 ¹⁵ Ωm or more.

  In addition, the electron amplification pore glass plate according to the present embodiment includes a plurality of through holes 14 having a circular shape in plan view arranged two-dimensionally at regular intervals. The plurality of through holes 14 have a hole diameter of 100 μm. In the following (for example, 30 to 100 μm, preferably 30 to 50 μm), the pitch of the array is 400 μm or less (for example, 50 to 400 μm, preferably 50 to 360 μm). In addition, although the lower limit of a hole diameter and a pitch is not specifically limited, The magnitude | size which an electron can pass by the magnitude | size which can be formed with the manufacturing procedure mentioned later may become a lower limit.

  Furthermore, it is assumed that the electronic amplification pore glass plate in the present embodiment has a thickness of 500 μm or less. If it is 400 micrometers or less, it can be said that it is suitable for the use of the substrate 10 for electronic amplification, However, Preferably it forms 300 micrometers or less, More preferably, it forms about 100-150 micrometers. In particular, considering that the through hole 14 has a hole diameter of 100 μm or less, if the plate thickness is about 100 to 150 μm, the aspect ratio (ratio of hole diameter to hole length) of the through hole 14 is suppressed from becoming excessive. can do.

<3. Manufacturing procedure of pore glass plate for electron amplification>
Next, the manufacturing procedure of the electron amplification pore glass plate configured as described above will be described.
FIG. 3 is an explanatory diagram showing an example of a manufacturing procedure of the electronic amplification pore glass plate in the present embodiment.

In the manufacture of the electronic amplification pore glass plate, first, as shown in FIG. 3 (a), a desired outer shape (for example, a rectangular shape of 300 mm × 300 mm) is formed to a desired thickness using a photosensitive glass such as “PEG3”. The formed flat plate-like member 11 is prepared.
Then, as shown in FIG. 3B, a photomask 15 on which a desired pattern is formed is overlaid on the prepared plate-like member 11, and ultraviolet rays 16 are applied to the plate-like member 11 through the photomask 15. Irradiate. Thereby, in the plate-like member 11, an oxidation-reduction reaction occurs at the ultraviolet irradiation site, and metal atoms are generated.
Thereafter, heat treatment is performed on the plate-like member 11 after irradiation with ultraviolet rays at a temperature of 450 to 600 ° C., for example. Then, in the plate-like member 11, as shown in FIG. 3C, metal atoms generated by ultraviolet irradiation aggregate to form a colloid, and this colloid serves as a crystal nucleus to form Li ₂ O.SiO ₂ (lithium metasilicate). ) Grows.
The Li ₂ O · SiO ₂ (lithium metasilicate) deposited here is easily dissolved in HF (hydrogen fluoride), and there is a difference in dissolution rate of about 50 times compared to the glass part not irradiated with ultraviolet light 16. is there. Therefore, after crystal growth by heat treatment, etching using HF is performed on the plate member 11 as shown in FIG. As a result, etching for removing the crystal portion 17 deposited by the heat treatment, that is, selective etching using a difference in dissolution rate with respect to HF is performed. As a result, the pattern of the photomask 15 is substantially omitted without using machining. A fine through-hole 14 with the same accuracy can be formed in the plate-like member 11.

  The plate-like member 11 after the through-holes 14 formed in this way remains a photosensitive glass such as “PEG3” as a forming material. Therefore, after the through hole 14 is formed by selective etching, the plate-like member 11 in which the through hole 14 is formed is further heat-treated as shown in FIG. The heat treatment at this time is performed under conditions different from the heat treatment for forming the through holes 14 performed previously. Specifically, heat treatment is performed at a temperature exceeding 1000 ° C., for example. Thereby, unlike the case of the heat treatment performed previously, the plate-like member 11 has a polycrystalline state in which fine crystals excellent in chemical durability are evenly precipitated in the glass and the crystallization progresses completely. Become. This corresponds to photosensitive crystallized glass such as “PEG3C” obtained by crystallizing photosensitive glass such as “PEG3”. That is, by performing the heat treatment again under conditions different from the heat treatment performed previously, an electron amplification pore glass plate 18 in which a plurality of through holes 14 are two-dimensionally arranged in a photosensitive crystallized glass such as “PEG3C” is obtained. It is obtained. The electron amplification pore glass plate 18 thus obtained is formed of photosensitive crystallized glass and is in a polycrystalline state in which crystallization has completely proceeded. Compared to the case where the glass is made of a porous glass, it has an advantage of excellent mechanical properties (see, for example, FIG. 2).

  In addition, after manufacturing the electronic amplification pore glass plate 18 according to the above-described procedure, each of the front and back surfaces of the electronic amplification pore glass plate 18 is made conductive such as Cu (copper) by sputtering, for example. By forming the conductive layer 12 made of an excellent material, the electronic amplification substrate 10 for the detector 1 is configured.

<4. Measurement procedure of ionized electrons in the detector>
Next, when the detector 1 is configured using the electron amplification substrate 10 formed based on the electron amplification pore glass plate 18 of the present embodiment as described above, the detector 1 uses the ionization electron. A procedure for performing measurement of particle diameter or electromagnetic waves by this measurement will be specifically described with reference to FIG. Here, the following description will be given by taking the case where X-rays are the detection target as an example.

The chamber 2 of the detector 1 is filled with a predetermined type of detection gas (for example, a mixed gas of Ar + CF ₄ ). Further, different voltages are applied to the drift electrode 3, the readout electrode 4, and the conductive layer 12 of the electronic amplification substrate 10 in order to draw electrons generated in the drift region 5 toward the readout electrode 4. Then, the electric fields E1, E2, and E3 are generated. That is, voltage is applied to each of the drift electrode 3, the readout electrode 4, and the conductive layer 12 of the electronic amplification substrate 10 so as to give a potential difference that increases the electron attracting force toward the readout electrode 4.

  When X-rays enter the chamber 2 in such a state, the incident X-rays ionize the gas in the drift region 5 in the chamber 2, and electrons are generated by this ionization action. At this time, since the electric field E <b> 1 is formed in the drift region 5, the generated electrons are attracted to the electron amplification substrate 10 side. Then, it tries to pass through the through hole 14 of the electronic amplification substrate 10.

  However, a high electric field is generated in the hole of the through hole 14 due to the formation of the electric field E2. For this reason, the speed of electrons passing through the through-hole 14 is accelerated by a high electric field and the kinetic energy increases, thereby giving energy to other surrounding electrons and releasing the electrons by a new ionization action. By repeating this, electrons are amplified, and as a result, they are amplified in an avalanche manner. That is, when an electron passes through the through hole 14, electron avalanche amplification occurs.

  The electrons multiplied by the electron avalanche amplification are attracted to the read electrode 4 side by the electric field E3 formed in the induction region. Then, the number of electrons is read out as a signal by the readout electrode 4. The readout electrode 4 that performs such signal readout is divided into small areas. Therefore, it can be specified in which area the electrons are measured.

  Depending on the type of gas in the chamber 2, light is excited in the drift region 5 together with or in place of electron ionization, and the excitation light may be amplified in the through hole 14. is there. In that case, by using an imaging element such as a CCD (Charge Coupled Device) as the readout electrode 4, it is also possible to measure as an imaging signal.

<5. Effects of this embodiment>
According to the electronic amplification pore glass plate 18 and the detector 1 described in the present embodiment, the following effects can be obtained.

  In the present embodiment, the electron amplification pore glass plate 18 is formed of photosensitive crystallized glass. Therefore, even when glass, which is a brittle material, is used as the constituent material of the electronic amplification substrate 10, the use of fine processing technology (specifically, pattern transfer technology using the photomask 15) used in the semiconductor manufacturing process is utilized. It is possible to obtain a sufficient strength that can realize thinning and the like. In other words, it is possible to realize a thin plate of the electronic amplification pore glass plate 18 that could not be realized with a glass material such as soda-lime glass or heat-resistant glass. It is possible to realize a finer hole diameter and arrangement pitch of the through holes 14 that could not be realized even with a glass material such as glass.

Therefore, the detector 1 according to the present embodiment causes the potential difference between the conductive layers 12 of the electronic amplification substrate 10 to be more than necessary by thinning the electronic amplification pore glass plate 18 constituting the electronic amplification substrate 10. even without increasing the, also even if electron amplification substrate 10 in the chamber 2 is only one, realized to obtain a sufficient gain when avalanche amplification (e.g. electron multiplication factor of more than 10 ⁴⁾ It becomes possible. If the plate thickness of the electron amplification pore glass plate 18 is thin, the inner wall area of the through-hole 14 can be reduced as compared with the case where the plate thickness is large, so that the electrons adhere to the wall surface in the hole. This is because the possibility of passing through the through hole 14 without increasing becomes high. That is, for example, if the thickness of the electron amplification pore glass plate 18 is large and the diameter of the through hole 14 is small, there is a high possibility that electrons will adhere to the wall surface in the hole before passing through the through hole 14. As a result, a sufficient gain may not be obtained. However, in the detector 1 according to the present embodiment, it is possible to solve this problem and obtain a sufficient gain. It should be noted that the thickness of the electron amplification pore glass plate 18 needs to be set in consideration of the fact that if the thickness is too thin, the gain may be reduced when the electron avalanche amplification is performed. This is presumably because the gap width (distance between the conductive layers 12 on the front and back of the substrate) necessary for amplification of the electron avalanche is reduced.

  Furthermore, the detector 1 in this embodiment can also effectively suppress the charge-up (charging) of the electronic amplification substrate 10. Since the inner wall area of the through hole 14 can be reduced through the thinning of the electron amplification pore glass plate 18 constituting the electron amplification substrate 10, ions like ions in the through hole 14 as well as electrons. This is because adhesion to the wall surface can be suppressed. In other words, even when a photosensitive crystallized glass having a higher insulation resistance than other glass materials is used as the electronic amplification pore glass plate 18, the charge-up is effectively suppressed by realizing the thin plate. It can be done. Further, the photosensitive crystallized glass forming the electron amplification pore glass plate 18 is less likely to be charged due to its lower insulation resistance than polyimide or the like, and it can be said that charge-up is unlikely to occur in this respect.

In addition, the detector 1 according to the present embodiment facilitates miniaturization of the hole diameter and the arrangement pitch of the through holes 14 by thinning the electronic amplification pore glass plate 18 constituting the electronic amplification substrate 10. This is because an excessive increase in the aspect ratio of the through-holes 14 and the like can be suppressed. Specifically, if the thickness of the electron amplification pore glass plate 18 is about 100 to 150 μm, the number of pixels per unit area in the electron amplification pore glass plate 18 is set to 10,000 pixels / cm ² or more. Can be easily realized. Here, the “number of pixels per unit area” refers to the number of through-holes 14 formed per unit area of the electronic amplification pore glass plate 18. That is, one through hole 14 corresponds to one pixel. As described above, in the detector 1 according to the present embodiment, the number of through holes 14 formed in the electronic amplification pore glass plate 18 directly affects the detection resolution. Therefore, the detector 1 in the present embodiment can improve the detection resolution (resolution of the detector 1) by miniaturizing the hole diameter and arrangement pitch of the through holes 14 due to the thinning of the electronic amplification pore glass plate 18. Therefore, this point is also very suitable as a detector application using electronic avalanche amplification. Moreover, by making it possible to use the pattern transfer technique using the photomask 15, not only can the through holes 14 be reduced in diameter and pitch, but also the diameters and pitches of the through holes 14 can be uniform. In this respect, it is very effective in improving the detection resolution.

  As described in the present embodiment, if a gain at the time of electronic avalanche amplification is ensured and detection resolution is improved, an image sensor such as a CCD is used as the readout electrode 4, for example. In addition to the X-rays mentioned in the example, an imaging detector having an excellent position resolution can be constructed for visible light to X-rays while using an electron avalanche amplification. In that case, as described above, it is very useful to increase the number of pixels per unit area in the electronic amplification pore glass plate 18 to increase the resolution.

  Further, in the present embodiment, the electron amplification pore glass plate 18 is formed of a photosensitive crystallized glass having a bending strength of 150 MPa or more when the through hole 14 is not formed. That is, since the electron amplification pore glass plate 18 is formed of photosensitive crystallized glass, the bending strength of more than 150 MPa, that is, glass materials such as soda-lime glass and heat-resistant glass, as well as “PEG3” Therefore, it has a bending strength that cannot be obtained even with a photosensitive glass such as the above. Therefore, by utilizing such excellent mechanical characteristics, even if it corresponds to the above-described thinning and miniaturization of the through-hole 14, it is possible to prevent the occurrence of breakage such as cracks. Can do. Moreover, by utilizing the excellent mechanical properties, it is possible to form a large-area electron amplification pore glass plate 18 that has been difficult to realize in the past, such as a 300 mm × 300 mm rectangular shape.

Further, in the present embodiment, the hole diameter of the through holes 14 in the electronic amplification pore glass plate 18 is 100 μm or less and the arrangement pitch is 400 μm or less. That is, the fine glass plate 18 for electronic amplification cannot be formed by mechanical processing such as a fine powder injection method, but is a fine processing technique used in the semiconductor manufacturing process (specifically, a pattern transfer technique using the photomask 15). The through-hole 14 is formed so as to be fine enough to be formed without using the above. Therefore, it is very suitable for improving the detection resolution in the detector 1.
In particular, with respect to the hole diameter of the through hole 14, the following effects can be obtained by setting it to 100 μm or less. If the hole diameter of the through-holes 14 is reduced (specifically, 100 μm or less), the arrangement pitch of the through-holes 14 can be reduced accordingly. As a result, the detection resolution can be improved.
Moreover, about the arrangement pitch of the through-holes 14 by setting it as 400 micrometers or less, the following effects are acquired. When the arrangement pitch of the through holes 14 is set to 400 μm or less, specifically, the arrangement pitch may be set to, for example, 50 to 400 μm. This is because if the thickness is less than 50 μm, the thickness of the electron amplification pore glass plate must be excessively reduced. If the arrangement pitch of the through holes 14 is 50 to 400 μm, the through holes 14 having a diameter of 30 to 350 μm can be formed, so that the detection resolution is good, the gain is good, and the detection efficiency can be maintained.

In the present embodiment, the thickness of the electronic amplification pore glass plate 18 is formed to be 500 μm or less. When the thickness is 400 μm or less, an electronic avalanche amplification can be caused when used for the electronic amplification substrate 10. However, in order to obtain a sufficient gain upon amplification of the electronic avalanche and to suppress charge-up, it is effective to reduce the thickness of the electronic amplification pore glass plate 18. From this, it is considered that the thickness of the electronic amplification pore glass plate 18 is preferably 300 μm or less. On the other hand, if the thickness of the electron amplification pore glass plate 18 becomes too thin, the avalanche amplification does not occur and the possibility of occurrence of discharge increases. Therefore, it is conceivable that the thickness of the electronic amplification pore glass plate 18 is more preferably about 100 to 150 μm. For example, in the case where the thickness of the electronic amplification pore glass plate 18 about 100-150 .mu.m, depending on the gas type and the applied voltage, can be realized to obtain the electron multiplication factor of more than 10 ⁴ .

<6. Modified example>
While embodiments of the present invention have been described above, the above disclosure is intended to illustrate exemplary embodiments of the present invention. That is, the technical scope of the present invention is not limited to the above exemplary embodiment.

  For example, in the above-described embodiment, the case where there is only one electronic amplification substrate 10 in the chamber 2 is illustrated. However, a plurality of electronic amplification substrates 10 may be provided in the chamber 2. In the detector 1 having a plurality of electronic amplification substrates 10, the configuration of the apparatus is complicated as compared with the case of only one substrate, but it is easy to increase the gain at the time of amplification of the electronic avalanche. It becomes feasible.

  Further, in the above-described embodiment, the case where the hole diameters of the through holes 14 in the electronic amplification pore glass plate 18 are 100 μm or less and the arrangement pitch is 400 μm or less is exemplified, but such a range is not necessarily limited. It is not limited to. For example, even if the thickness of the electron amplification pore glass plate 18 is 400 μm, the diameter of the through holes 14 formed therein is 200 μm, and the arrangement pitch is 400 μm, the electron amplification pore glass is formed. By constructing the electronic amplification substrate 10 using the plate 18, electronic avalanche amplification can be caused.

  Next, an Example is given and this invention is demonstrated concretely. However, it is needless to say that the present invention is not limited to the following examples.

Example 1
In Example 1, as shown in FIG. 4, an electronic amplification porous glass plate 18 having a plate thickness of 100 μm in which through holes 14 are formed with a hole diameter of 30 μm, an array pitch of 50 μm, and a resolution per unit area of 40000 pixels / cm ^2. The following simulation was performed on the electronic amplification substrate 10 in which the conductive layer 12 having a thickness of 1 μm was formed on the front and back surfaces. The electronic amplification substrate 10 having such a configuration was placed in an environment filled with a mixed gas of CF ₄ 10% and Ne 90% at a temperature of 300 K and a pressure of 1 atm, and a potential difference of 500 V was given to each conductive layer 12. As shown in FIG. 5, it was found that the electric field converged in the hole of the through hole 14, and the electrons that entered the hole of the through hole 14 were accelerated as shown in FIG. 6 or FIG. . That is, it was confirmed that even when the electron amplification pore glass plate 18 having a plate thickness of 100 μm was used, it was possible to cause an electron avalanche amplification in the through hole 14.

(Example 2)
In Example 2, as shown in FIG. 8, the through-hole 14 has a hole diameter of 50 μm, an array pitch of 70 μm, and a resolution per unit area of 20408 pixels / cm ^2. The following simulation was performed on the electronic amplification substrate 10 in which the conductive layer 12 having a thickness of 1 μm was formed on the front and back surfaces. The electronic amplification substrate 10 having such a configuration was placed in an environment filled with a mixed gas of CF ₄ 10% and Ne 90% at a temperature of 300 K and a pressure of 1 atm, and a potential difference of 500 V was given to each conductive layer 12. As shown in FIG. 9, it was found that the electric field converged in the hole of the through hole 14 and the electrons that entered the hole of the through hole 14 were accelerated as shown in FIG. 10 or FIG. . That is, here too, as in the case of Example 1 described above, even when the electron amplification pore glass plate 18 having a plate thickness of 100 μm is used, the electron avalanche amplification is caused in the hole of the through hole 14. It was confirmed that it was possible.

(Example 3)
In Example 3, as shown in FIG. 12, through-holes 14 are formed with a hole diameter of 100 μm, an arrangement pitch of 360 μm, and a resolution per unit area of 774 pixels / cm ^2. An electronic amplification substrate 10 configured using the above was placed in the chamber 2 of the detector 1. The chamber 2 is filled with a mixed gas of Ne + CF _{4 at} a pressure of 1 atm, and 6 keV X-rays collimated at 100 μmφ from an external radiation source are incident thereon. Further, in the chamber 2, the distance between the drift electrode 3 and the electron amplification substrate 10 is 5 mm, the potential difference ΔV _Drift applied thereto is 50 V, and the distance between the electron amplification substrate 10 and the readout electrode 4 is 2 mm. Each is arranged so that the applied potential difference ΔV _Induction is 100V. Under such circumstances, while providing a variable potential difference (gap potential) ΔV _GAP between the conductive layers 12 in the electronic amplification substrate 10, the readout electrode 4 and the conductive layer 12 on the side of the readout electrode 4 are used. When the gain characteristics during the electronic avalanche amplification were examined, the results shown in FIG. 13 were obtained. According to this result, when the potential difference ΔV _GAP of each conductive layer 12 is about 580 V, even when only one electronic amplification substrate 10 is used, a sufficient gain for amplification of an electronic avalanche, that is, about 10 ⁴ is obtained. It can be seen that an electron multiplication factor is obtained. As described above, in Example 3, the resolution is lower than that in Example 8 described later, but the electron multiplication factor can be 10 ⁴ or more.
If photosensitive crystallized glass is used as the electronic amplification pore glass plate 18, the insulation resistance is higher than that of glass materials such as soda-lime glass and heat-resistant glass. Therefore, as shown in FIG. A gap-out signal can also be obtained from the layer 12. The gap out signal may be used as a trigger signal for instructing the detector 1 to start a predetermined operation, for example.

Example 4
In Example 4, under the same situation as in Example 3 (see FIG. 12), the potential difference ΔV _GAP of each conductive layer 12 is set to about 540 V, and the readout electrode 4 and the conductive layer on the side of the readout electrode 4 are set. When the energy resolution was examined at 12, a result as shown in FIG. 14 was obtained. Here, “energy resolution” refers to an index representing the accuracy of radiation energy measurement. When measuring energy such as X-rays, if the total energy is lost in the detector, the energy spectrum becomes a line spectrum in principle, but in an actual detector, the distribution spectrum has a certain spread. Detected. An energy resolution represents the spread of the spectrum distribution, and the narrower the spread, the higher the detection capability (accuracy). According to the result of FIG. 14, the energy resolution is about 15.7% for the gap-out signal from the conductive layer 12 and about 17.2% for the anode signal from the readout electrode 4, and a glass material such as soda-lime glass is used. It can be seen that the spread is narrow compared with the case where it is used (for example, energy resolution of about 23%), and a good detection result is obtained. This is because, by using photosensitive crystallized glass as the electron amplification pore glass plate 18, each through hole 14 can be miniaturized, and each hole has no variation and the uniformity is kept high. This is probably because of this.

(Example 5)
In the fifth embodiment, under the same situation as in the third embodiment (see FIG. 12), the potential difference ΔV _GAP of each conductive layer 12 is set to about 530 V, and on / off of X-ray irradiation from the radiation source is illustrated. As shown in FIG. 15 (a), switching is performed with time. In that case, when the gain fluctuation with the passage of time was examined, it was found that there was no fluctuation in the peak value of the gain with the passage of time as shown in FIG. This is considered because the charge-up of the electronic amplification substrate 10 can be effectively suppressed. For comparison, FIG. 15C shows gain fluctuations with time when a general GEM made of polyimide is used. According to this result, it is recognized that a decrease of about 28% occurs in 10 minutes immediately after the irradiation, but this can effectively suppress the charge-up unlike the case of using the photosensitive crystallized glass. It is thought that it is not.

(Example 6)
In Example 6, under the same situation as in Example 3 (see FIG. 12), the potential difference ΔV _GAP of each conductive layer 12 is set to about 530 V, and the rate (Hz) of X-ray irradiation from the radiation source is set. Made variable. In that case, when the peak channel and energy resolution of the energy spectrum accompanying the variable rate were examined, it was found that the fluctuation due to the variable rate was suppressed in all cases as shown in FIG. This is considered to be because the charge-up of the electronic amplification substrate 10 can be effectively suppressed as in the case of the fifth embodiment described above.

(Example 7)
In Example 7, under the same situation as in Example 3 (see FIG. 12), the potential difference ΔV _GAP of each conductive layer 12 was set to about 530 V, and the position of X-ray irradiation from the radiation source was varied. . The position here is a planar position of X-ray irradiation with respect to the electronic amplification substrate 10. In that case, when the peak channel of the energy spectrum accompanying the X-ray irradiation position change was examined, the result as shown in FIG. 17 was obtained. According to this result, it can be seen that even if the irradiation position of the X-ray is changed, the peak channel is constant within ± 3% with respect to the change of the irradiation position of, for example, about 15 mm. This is because, by using photosensitive crystallized glass as the electron amplification pore glass plate 18, each through hole 14 can be miniaturized, and each hole has no variation and the uniformity is kept high. This is probably because of this.

(Example 8)
In Example 8, the through-holes 14 are formed by using an electron amplification pore glass plate 18 having a plate thickness of 130 μm formed with a hole diameter of 50 μm, an array pitch of 70 μm, and a resolution per unit area of 20408 pixels / cm ^2. The amplification substrate 10 was placed in the chamber 2 of the detector 1. The chamber 2 is filled with a mixed gas of Ne + CF _{4 at} a pressure of 1 atm, and 6 keV X-rays collimated at 100 μmφ from an external radiation source are incident thereon. Further, in the chamber 2, the distance between the drift electrode 3 and the electron amplification substrate 10 is 5 mm, the potential difference ΔV _Drift applied thereto is 50 V, and the distance between the electron amplification substrate 10 and the readout electrode 4 is 2 mm. Each is arranged so that the applied potential difference ΔV _Induction is 100V. Under such circumstances, while providing a variable potential difference (gap potential) ΔV _GAP between the conductive layers 12 in the electronic amplification substrate 10, the readout electrode 4 and the conductive layer 12 on the side of the readout electrode 4 are used. When the gain characteristic at the time of amplification of the electronic avalanche was examined, a result as shown in FIG. 18 was obtained. According to this result, it can be seen that if the potential difference ΔV _GAP of each conductive layer 12 is about 600 V, an electron multiplication factor of about 10 ³ can be obtained. According to the present embodiment, it can be seen that the electronic amplification magnification is at a high level while the resolution is high with a fine arrangement pitch.

  DESCRIPTION OF SYMBOLS 1 ... Detector, 2 ... Chamber, 3 ... Drift electrode, 4 ... Read-out electrode, 10 ... Electronic amplification board, 11 ... Plate-shaped member, 12 ... Conductive layer, 13 ... Laminated body, 14 ... Through-hole, 18 ... Electron Amplified pore glass plate

Claims (6)

A porous glass plate for electron amplification used in a detector for measuring ionization electrons using electron avalanche amplification in gas,
A plurality of through holes arranged two-dimensionally in the plate-like member are provided,
The plate-like member is formed of photosensitive crystallized glass obtained by crystallizing photosensitive glass. An electronic amplification pore glass plate, wherein: The pore glass plate for electronic amplification according to claim 1, wherein the photosensitive crystallized glass has a bending strength of 150 MPa or more when the through hole is not formed. The pore glass plate for electron amplification according to claim 1 or 2, wherein the plurality of through holes are formed with a hole diameter of 100 µm or less. The pore glass plate for electron amplification according to any one of claims 1 to 3, wherein the plurality of through holes are formed with an arrangement pitch of 400 µm or less. The plate-like member is formed to have a plate thickness of 500 μm or less. The electron amplification pore glass plate according to claim 1, wherein the plate-like member is formed to have a thickness of 500 μm or less. A plurality of through-holes arranged two-dimensionally in a plate-like member, and the plate-like member is made of photosensitive crystallized glass obtained by crystallizing photosensitive glass. Plates,
An electrode that has a conductive layer formed on the front and back surfaces of the electron amplification pore glass plate, and forms an electric field in the through hole by applying a potential difference between the front and back surfaces;
A chamber for placing the electron amplification pore glass plate and the electrode in a gas;
A detector configured to perform measurement of ionized electrons using electron avalanche amplification caused by an electric field formed in the through hole in the gas.